Communication networks are increasingly relied on by individuals and businesses to exchange information. For example, email provides a convenient and inexpensive means for exchanging information. In addition to allowing for the exchange of textual messages, email allows users to attach computerized files for transmission to the recipient. However, email that is sent across the Internet is relatively easy for even a casual hacker to intercept and read, unless its contents are encrypted. Therefore, the exchange of sensitive documents over unprotected networks such as the Internet can result in the inadvertent disclosure of sensitive information.
In order to ensure the security of information delivered over the Internet, various encryption methods have been developed. For example, pretty good privacy (PGP) applies asymmetric encryption to prevent unauthorized access to information. PGP encryption methods require that the parties to an exchange of information first exchange their asymmetric public keys. In addition, the parties must install the same encryption software. Accordingly, the use of PGP mail requires prior arrangement of software licenses and the configuration of encryption keys at both ends of the email communication.
Other methods for providing secure access to documents over the public Internet also require the use of specialized software installed at both ends of a communication channel, and coordinated configuration. Accordingly, such methods cannot be used on an adhoc basis.